Curtain walls are widely used as exterior sheathing of buildings, especially of the commercial or institutional type. Curtain walls typically consist of glass panels defining a major portion of the exterior surface of the building, with structural members separating the glass panels. A type of curtain wall is known as VEC facade, or structural glazing, and is characterized by the absence of exposed fastener devices between adjacent glass panels, from an outer point of view. In VEC facades, a transparent/translucent panel is glued (or secured) to a sash off site to form a glazing panel, which sash will cooperate with the structural members when the glazing panel is connected to the framing.
One of the major costs associated with curtain walls is the manpower required at installation. More specifically, once the structural members (e.g., mullions and transoms) have been secured to the building framing, a substantial amount of work is required to secure the glazing panels between the structural members. The glazing panels must be precisely positioned between the structural members, and supported in position while fasteners are implanted about the periphery of a sash of the glazing panel.
In the case of VEC facades, space is limited between adjacent glass panels for esthetic considerations, thereby rendering the implanting of fasteners more difficult. The spacing between adjacent panels in VEC facades is such as to allow workers to implant the fasteners to secure the glass panels to the vertical members.
The amount of work and time required to install curtain walls is substantial, and is associated with other problems pertaining to the logistics of construction sites. For instance, the amount of time required is often in the order of several days, thereby potentially exposing the construction sites to problematic weather conditions, such as rain and wind. This may cause delays in scheduling on the construction site. Moreover, the amount of time required delays the occupancy of the building.
U.S. Pat. No. 5,263,292 (hereinafter “patent '292”), issued to Holland et al. on Nov. 23, 1993, describes a building panel system in which anchor sockets are secured to the building framing. The anchor sockets are shaped so as to receive in snap-fit engagement legs of connectors secured to the glass panels. A pressure gasket is then forced into the interstitial space between the legs of adjacent panels, so as to prevent the escape of the legs from their engagement with the anchor sockets.
The building panel system of patent '292 describes a simplified installation of the glass panel to the structural members in that the glass panels are snap-fitted to the structural members without additional fasteners. However, the legs are subjected to plastic deformation when the glass panels are connected to the structural members. This requires a nonnegligible amount of force to secure the glass panels to the structural members. Also, the integrity of the connection between the glass panels and the structural members is dependent on these legs that undergo plastic deformation, whereby safety devices such as the pressure gasket are required. Finally, the configuration of the anchoring means is such that a glass panel must be destroyed to be removed from the structural members. It is occasionally required to remove glass panels, for instance when moving large furniture. In such cases, removing a glass panel becomes a costly solution.